import os
import subprocess
import logging

# $ DATASET_PATH=/path/to/dataset

# $ colmap feature_extractor \
#    --database_path $DATASET_PATH/database.db \
#    --image_path $DATASET_PATH/images

# $ colmap exhaustive_matcher \
#    --database_path $DATASET_PATH/database.db

# $ mkdir $DATASET_PATH/sparse

# $ colmap mapper \
#     --database_path $DATASET_PATH/database.db \
#     --image_path $DATASET_PATH/images \
#     --output_path $DATASET_PATH/sparse

# $ mkdir $DATASET_PATH/dense


def run_colmap(basedir, match_type):
    """Simple wrapper for COLMAP"""

    logfile_name = os.path.join(basedir, 'colmap_output.txt')
    logfile = open(logfile_name, 'w')

    feature_extractor_args = [
        'colmap', 'feature_extractor',
            '--database_path', os.path.join(basedir, 'database.db'),
            '--image_path', os.path.join(basedir, 'images'),
            '--ImageReader.single_camera', '1',
            #'--SiftExtraction.use_gpu', '0', # Use CPU only, comment to use GPU
    ]
    logging.debug("Extracting features.")
    feat_output = subprocess.check_output(feature_extractor_args, universal_newlines=True)
    logfile.write(feat_output)

    exhaustive_matcher_args = [
        'colmap', match_type,
            '--database_path', os.path.join(basedir, 'database.db'),
    ]

    logging.debug("Matching features.")
    match_output = subprocess.check_output(exhaustive_matcher_args, universal_newlines=True)
    logfile.write(match_output)

    p = os.path.join(basedir, 'sparse')
    if not os.path.exists(p):
        os.makedirs(p)

    mapper_args = [
        'colmap', 'mapper',
            '--database_path', os.path.join(basedir, 'database.db'),
            '--image_path', os.path.join(basedir, 'images'),
            '--output_path', os.path.join(basedir, 'sparse'), # --export_path changed to --output_path in colmap 3.6
            '--Mapper.num_threads', '16',
            '--Mapper.init_min_tri_angle', '4',
            '--Mapper.multiple_models', '0',
            '--Mapper.extract_colors', '0',
    ]

    logging.debug("Creating sparse map")
    map_output = subprocess.check_output(mapper_args, universal_newlines=True)
    logfile.write(map_output)
    logfile.close()

    logging.info("Finished running COLMAP. Logfile written in %s",
            logfile_name)